As was foretold, I put the flat colors into my storefronts file. I also added the weird archway building next door to Dirk's office, as well as some more random shops on the other side.
As with all new techniques, I had to take a step back and evaluate just how often I should do this in the future. I still think it was a good idea for these storefronts, because they will get reused in future scenes. I probably will not take the time for any location in one-off scenes however.